CN1791300B - Multi-layered circuit board and manufacturing method of multi-layered circuit board - Google Patents

Abstract

Provided are a multilayer circuit board and a method of manufacturing the same, which enable proper mounting of electronic components without hindering the performance of the electronic components. Power supply terminals (pins) of electronic components to be mounted on the surface of the multilayer circuit board are inserted into the plated through holes to be connected with the first conductive layer. A detection portion is provided on the second conductive layer on the back of the first conductive layer, the detection portion having a detection hole formed coaxially with the through hole and having a diameter larger than that of the through hole. A hole with a large diameter is formed from the back along the through hole by means of a tool while applying a voltage between the second conductive layer and the tool. The depth of the hole is set based on electrically conducting the tool with the detection hole. Unnecessary plating of through holes can be removed through large holes.

Description

Multilayer circuit board and its manufacturing method

technical field

The present invention relates to a multilayer circuit board formed by stacking a plurality of substrates composed of conductive layers and insulating layers into one body, and to a method for manufacturing the multilayer circuit board. the

Background technique

Conventionally, in order to drill a hole through a multilayer circuit board, there has been a technique of detecting the surface height of a point to be machined and drilling the hole to a specified depth based on the detected height, as described in Japanese Patent Laid-Open No. published in 2001-341052. It improves the accuracy of the depth of the hole to be machined. However, due to variations in the thickness of the multilayer circuit board, it is not always possible to stably form blind holes for connecting upper and lower conductive layers by this method. the

Subsequently, there has been proposed a technique of providing a measurement area in advance in each laminated conductive layer, exposing each measurement area before drilling, and drilling a hole while confirming the position of the tool in the height direction, as in Japanese Patent Disclosed in Publication No. 2004-63771. It allows blind holes for connecting upper and lower conductive layers to be stably formed. the

Incidentally, a power supply terminal (power supply pin) of an electronic part such as an IC package, for example a pin, is connected to a required conductive layer when the IC package is mounted on a multilayer circuit board as follows. That is, a hole to reach a desired conductive layer is drilled from the surface of the multilayer substrate and plating is performed to form a plated layer on the inner face of the hole. Then, a power supply terminal (pin) or the like is inserted into the hole and soldering is performed to electrically connect the power supply terminal (pin) with a desired conductive layer through the plated hole. the

Fig. 4 is a sectional view of a conventional multilayer circuit board. the

The multilayer circuit board 1 shown in the figure is formed as follows. That is, the multilayer circuit board 1 is formed by sequentially laminating the third substrate 2 composed of the conductive layer 2a and the insulating layer 2b combined with each other, the second substrate 3 composed of the conductive layers 3a and 3c and the insulating layer 3b combined with each other, The first substrate 4 composed of the conductive layer 4a and the insulating layer 4b combined with each other, and the surface substrate 5 composed of the conductive layer 5a and the insulating layer 5b combined with each other are formed by combining them with each other by means of an adhesive and by heat treatment. Forming. Here, although circuit patterns are formed on the conductive layers 3a, 3c, and 4a, ie, the inner laminate layer, there are cases where circuit patterns are formed and no circuit patterns are formed on the surface conductive layer 5a and the back conductive layer 2a. In the case of the second substrate 3, the conductive layer 3a is electrically connected to the conductive layer 3c' via the plating layer 7 formed on the connection hole 6 by plating. the

Next, holes 8 for connecting power supply terminals of electronic components such as pins to the desired conductive layer (first conductive layer 4a in the case of FIG. In this paper, it is called the surface side) to drill. In addition, if necessary, a connection hole for connecting the surface conductive layer 5a and/or the back conductive layer 2a with the inner conductive layers 3a and 3c is drilled. the

Subsequently, the circuit pattern is formed by etching immediately after the circuit pattern is formed on the conductive layer 5 a on the surface side and the conductive layer 2 a on the back side opposite to the surface side, or when no circuit pattern is formed on the conductive layers 5 a and 2 a Thereafter, the plated layer 9 is formed by plating the inside of the power feed connection hole (not shown in FIG. 4 ) connecting the surface conductive layer 5a and/or the back conductive layer 2a with the inner conductive layers 3a and 3c . the

Although the plating is normally carried out under sufficient control, there is a case where the thickness of the plating layer 9 at the bottom of the hole 8 becomes too thick, or the diameter of the plating layer 9 at the bottom of the hole 8 becomes smaller compared with that on the inlet side situation, as shown in the figure. When the plating layer 9 is thus formed, there are cases where the edges of the power supply terminals cannot be inserted to a desired depth and electronic components appear above the surface of the multilayer circuit board 1 . If the electronic parts are present on the surface of the multilayer circuit board, power supply terminals (pins) are easily damaged by vibration or the like, thereby reducing their reliability. In addition, there arises a problem that if the external dimensions of a multilayer circuit board as a product incorporating electronic components become large, it may not be stored in an electronic device using the multilayer circuit board. the

In this case, it is conceivable to avoid dispersion or local increase in plating thickness by forming the hole 8 as a through hole. But if this via hole is formed close to the circuit pattern on the back side, there are cases where electronic parts cause malfunction due to noise that is the result of electromagnetic effect caused by one of them to the other. Therefore, it is necessary to remove unnecessary plating when the holes 8 for positioning the power supply terminals are formed as through holes after plating. the

However, unnecessary plating cannot be accurately removed by the technique of Japanese Patent Laid-Open No. 2004-63771 because the tool is electrically connected to a desired conductive layer through the plating when removing the unnecessary plating. the

Accordingly, an object of the present invention is to provide a multilayer circuit board and a method of manufacturing the same, which enable electronic components to be properly mounted without hindering the performance of the electronic components. This object is achieved by combining the features described in the independent claims of the invention. The dependent claims define preferred embodiments of the invention. the

Contents of the invention

In order to solve the above-mentioned problems, according to a first aspect of the present invention, there is provided a multilayer circuit board formed by laminating and combining a plurality of substrates composed of conductive layers and insulating layers, having: through holes, It penetrates from the surface of the multilayer circuit board to its back surface while making contact with the surface conductive layer provided on the surface of the substrate located on said surface, and with the first conductive layer located below and within the surface conductive layer ; The conductive plating layer is plated on the inner peripheral surface of the through hole to electrically connect the surface conductive layer with the first conductive layer; the detection part is arranged on the second conductive layer, and the second conductive layer is opposite to the first conductive layer. The conductive layer is located on the back side, and has a detection hole formed coaxially with the through hole and having a diameter larger than that of the through hole; A through hole is formed coaxially along the through hole from the back surface to at least the second conductive layer, wherein by forming the large hole, a portion of the detection hole of the detection portion is exposed to the large hole. the

Thus, since the connection hole for connecting the power supply terminal of the electronic part is formed as a plated through hole, and the hole reaching the detection hole is formed along the through hole from the back of the multilayer circuit board, as described above, Plating formed on the through hole can be definitely removed. Therefore, it becomes possible to provide a multilayer circuit board that allows electronic components to be properly mounted and does not hinder the operation of the electronic components. the

As a multilayer circuit board, such one is used, which has: a through hole penetrating from the surface of the multilayer circuit board to its back side while being in contact with a surface conductive layer provided on the surface of the substrate located on said surface, and in contact with the first conductive layer located under and within the surface conductive layer; a conductive plating layer plated on the inner peripheral surface of the through hole to electrically connect the surface conductive layer with the first conductive layer; and the detection part, Provided on the second conductive layer, from the first conductive layer, the second conductive layer is located on the back side, and has a detection hole, which is formed coaxially with the through hole and whose diameter is larger than the diameter of the through hole, (for example, as shown in shown in 1). the

The multilayer circuit board is an intermediate product, and eventually it becomes a multilayer circuit board in which large holes are formed (see FIG. 3 ). Although it is an intermediate product, it is shipped as a product from a substrate manufacturer and it is manufactured as a final product at the product manufacturer. the

Preferably, the first conductive layer is the conductive layer on the surface side of the second substrate adjacent to the surface substrate having the surface conductive layer; and the second conductive layer is the surface side of the third substrate adjacent to the backside of the second substrate the conductive layer. the

According to a second aspect of the present invention, there is provided a method of manufacturing a multilayer circuit board formed by laminating a plurality of substrates composed of conductive layers and insulating layers, by which a Connection holes for power supply terminals of electronic components to be mounted on a multilayer circuit board having a first conductive layer on the surface of the multilayer circuit board, the method having the steps of: A detection part with a detection hole is formed on the upper surface, and the second conductive layer is on the back side relative to the first conductive layer; a through hole is formed, which penetrates from the surface of the multilayer circuit board to the back surface, and at the same time is arranged on the surface of the multilayer circuit board. contacting the surface conductive layer on the surface of the substrate, and contacting the first conductive layer located inside, and not contacting the detection hole by having a diameter smaller than that of the detection hole; plating the inner surface of the through hole; and From the backside of the multilayer circuit board along the through hole, through a tool having a diameter larger than that of the detection hole, while applying a predetermined voltage between the tool and the second conductive layer on which the detection part is provided, based on the detection Detection of holes additionally drilling a hole having a large diameter and a predetermined depth, wherein the connection hole is formed through a through hole between the surface conductive layer and the first conductive layer, wherein the plating is left on the inner peripheral surface thereof; Wherein the first conductive layer is a conductive layer on the surface side of the second substrate adjacent to the surface substrate having the surface conductive layer; and the second conductive layer is a conductive layer on the surface side of the third substrate adjacent to the back side of the second substrate. layer. the

Thereby, a multilayer circuit board that allows electronic components to be properly mounted and does not hinder the operation of the electronic components can be easily formed by precisely extending from the back of the multilayer circuit board to the through hole through the additional step. The predetermined depth forms a hole having a large diameter, and simultaneously forms a connection hole for connecting a power supply terminal of an electronic part as a plated through hole by precisely removing unnecessary plating. the

The predetermined depth in the additional step may be a depth determined based on a position of the tool when the voltage becomes a preset value or less. the

It is therefore possible to accurately detect the depth of a hole having a large diameter and being drilled by the tool, and by drilling until the voltage applied between the tool and the second conductive layer on which the detection portion is provided becomes preset value or below, a hole having a large diameter and a predetermined depth is stably formed. the

The manufacturing method of the multilayer circuit board further includes the steps of: beside the connection through hole, drilling a detection through hole at a position connected to the second conductive layer having the detection part, and plating the inner surface of the detection through hole, wherein In the further step, the predetermined voltage is applied between the second conductive layer having the detection portion and the tool via the plating of the detection via hole. the

By plating the detection through hole, the voltage between the second conductive layer having the detection portion and the tool can be easily measured by providing a measuring probe or the like, and a hole having a predetermined depth and a large diameter can be easily and accurately measured. formed without the required machining for exposing the second conductive layer. the

Description of drawings

FIG. 1 is a cross-sectional view of a multilayer circuit board to which the present invention is applied during a machining process. the

Fig. 2 is a plan view of a substrate of the present invention on which a detection portion is provided. the

FIG. 3 is a cross-sectional view of a multilayer circuit board to which the present invention is applied immediately before electronic parts are mounted. the

Fig. 4 is a sectional view of a conventional multilayer circuit board. the

Detailed ways

The invention will now be described based on preferred embodiments shown in the drawings, which are not intended to limit the invention but illustrate the invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention. the

1 is a cross-sectional view of a multilayer circuit board to which the present invention is applied during a machining process, FIG. 2 is a plan view of a substrate on which a detection portion is provided, and FIG. 3 is a multilayer circuit board to which the present invention is applied just before mounting electronic components. A cross-sectional view of a multilayer circuit board. The same parts or the same functions as those in FIG. 4 will be denoted by the same reference numerals, and repeated description thereof will be omitted here. the

Although the multilayer substrate shown in FIG. 1 becomes substantially the same as the multilayer circuit board shown in FIG. In that a conventional blind hole (hole 8 in FIG. 4 ) for inserting a power terminal is formed as a through hole (with the same diameter as hole 8 ), in that a detection through hole 23 is newly provided and in that a pad (pad) 2ap1, 2ap2 and 5ap, namely the conductive layer. That is, this multilayer substrate 1 has a surface substrate 5, a first substrate 4, a second substrate 3, and a third substrate 2 on the back in order from the surface side on which electronic components are mounted, and these substrates are laminated as one. The surface substrate 5 has a surface conductive layer 5c for connection holes formed together with a surface conductive layer 5a for circuit patterns on the surface of the insulating layer 5b, and the first substrate 4 has a first conductive layer 4a formed on the surface of the insulating layer 5b. The surface side of the insulating layer 4b is also connected to the connection hole. The second substrate 3 has a first conductive layer 3c' and a second conductive layer 3c formed on the surface side of the insulating layer 3b, and a conductive layer 3a formed on the back side of the insulating layer 3b. The conductive layers 3c' and 3a are electrically connected to each other through the connection hole 6 having the plating layer 7. As shown in FIG. The third substrate 2 has a conductive layer 2a on the back of an insulating layer 2b. the

Note that the surface conductive layer 5c for the connection hole may have a circuit pattern formed thereon, or may be dedicated to the connection hole like a pad. It may also be a conductive layer formed by a plating process described later. the

This will be explained in order. the

As shown in FIG. 1, a through hole 20 penetrating from the surface of the multilayer circuit board 1 to the back is formed so as to be in contact with the surface conductive layer 5c and the first conductive layer 4a connected to the connection hole, and the inner periphery of the through hole The surface is plated to form a plated layer 21. the

As shown in FIG. 2 , the axis of the through hole 20 (hole 8 in FIG. 4 ) for positioning the power supply terminal of the electronic component is assumed to be O. As shown in FIG. The detecting portion 35 having the detecting hole 22 coaxial with the axis O and having a larger diameter than the through hole 20 is formed by the second conductive layer 3c of the substrate 3 disposed on the back side of the insulating layer 4b and close to the first conductive layer 4a. the

In addition, pads, that is, conductive layers 2ap1, 2ap2, and 5ap are provided on the surface substrate 5 and the back substrate 2, centering on the axis of the via hole 20 and the axis of the detection via hole described later, as shown in FIG. the

Next, steps for manufacturing the multilayer circuit board of the present invention will be described. the

Step 1: Through-holes 20 for inserting and positioning power terminals (pins) of electronic components to be provided on the surface are drilled. The detection vias 23 connected to the conductive layer 3c are also drilled. Note that the detection via hole 23 is provided at any position within the second conductive layer 3c. the

Step 2: The plating layer 21 is formed on the inner surface of the through hole 20 and the plating layer 24 is formed on the inner surface of the detection through hole 23 through the plating process, respectively. the

Step 3: through the tool 30 whose diameter is larger than the diameter of the detection hole 22, and simultaneously apply a preset voltage of, for example, 5V between the tool 30 and the plating layer 24, that is, the conductive layer 3c, from the back side along the through hole 20 (axis O) to perform drilling. When the voltage between the tool 30 and the conductive layer 3c becomes a predetermined voltage such as 2V or below, it is judged that the tool 30 has reached the position of the conductive layer 3c, ie is in contact with the conductive layer 3c. Then, if eg the conductive layer 3c is close to the conductive layer 4a, the drill is stopped at that moment. In addition, for example, in connection with the arrangement of the circuit pattern, when the detection part 35 is arranged on the conductive layer 3a instead of the conductive layer 3c on the back side, the drilling is carried out further by a preset distance from the position. the

Since the diameter of the tool 30 is larger than the outer diameter of the plating layer 21 , a hole 32 with a large diameter is pierced by the tool 30 from the back surface along the through hole 20 (axis O), as shown in FIG. 3 . The hole 32 is drilled to a depth such that the tool 30 is electrically connected to the detection hole 23 formed through the conductive layer 3c. Therefore, the plated layer 21 of the through hole 20 is stably removed up to a position below the conductive layer 3c or slightly above the conductive layer 3c where the detecting portion 35 is located. the

The multilayer circuit board 1 is manufactured in the same manner as the following conventional method. the

Step 4: The power terminal (pin) is inserted into the through-hole 20 in which the plating layer 21 is formed to position the electronic part. the

Step 5: Connect the power supply terminal to the plating layer 21, ie, the conductive layer 4a, by means of soldering. the

Note that when no circuit patterns are formed on the conductive layers 2a and 5a, circuit patterns are formed on the conductive layers 2a and 5a by etching or the like after step 2 is ended. the

Here, the position of the conductive layer where the detection section 35 is provided will be described. It is desirable to dispose the detecting portion 35 on the conductive layer closest to the conductive layer to which the power supply terminal is connected to accurately remove the plating layer 21 on the back side from the conductive layer to which the power supply terminal is connected. However, there are cases where either one of the edge of the power supply terminal and the conductive layer provided with the detection portion 35 causes an electromagnetic effect on the other. On the other hand, if the detection part 35 is separated from the conductive layer to which the power terminal is connected to prevent electromagnetic effects, it becomes difficult to remove the plating layer 21 precisely because the thickness of the substrate varies depending on lamination conditions. Therefore, it is desirable to decide the conductive layer in which the detection part 35 is provided according to the product. the

Note that even if the length of the power supply terminal (pin) of the electronic part is longer than the depth from the surface to the first conductive layer 4a, and there is a possibility of reaching the conductive layer when connecting the power supply terminal (pin) of the electronic part with, for example, the conductive layer 4a The length of 3c, the hole 32 pierced by the tool 30 has a diameter that is significantly larger than the diameter of the plated through hole 20 . Therefore, the power terminal inserted into the plated layer 21 will not be in contact with the conductive layer 3c having a large diameter, and will not come close to exert electromagnetic influence. In addition, even if a certain amount of molten solder in step 5 permeates into the narrow gap between the plating layer 21 of the through hole 20 and the power supply terminal due to capillary phenomenon, it does not reach the hole 32 having a large diameter. In addition, even if a very small amount of solder reaches the upper end of the large hole 32, the solder will not reach the conductive layer 3c because the gap between the power supply terminal and the large hole is large and capillarity stops. the

The detection via 23 connected with the conductive layer 3c is provided in this embodiment, so that the conductive layer 3c does not need to be exposed, for example, by drilling, and the measuring probe can be easily added when measuring the voltage between the tool 30 and the conductive layer 3c. set up. the

Note that work efficiency can be further improved by providing means for automatically positioning the voltage detection probe to be in contact with the detection through hole 23 (plating layer 24 ) on the machining table for mounting the multilayer circuit board 1 . the

In addition, since the pads 2ap1, 2ap2, and 5ap are provided in this embodiment, the plating layers 21 and 24 can be stably formed. Note that pads 2ap1, 2ap2 and 5ap may not always be provided. In addition, if the conductive layer 3 c on which the detection portion 35 is provided is made conductive, for example, by exposing it, it is not necessary to provide the detection via hole 23 . the

Although the invention has been described by way of example embodiments, it should be understood that those skilled in the art can make many changes and substitutions within the spirit and scope of the invention. It is evident that embodiments with such modifications also fall within the scope of the invention as defined in the appended claims. the

Claims (3)

1. A method of manufacturing a multilayer circuit board formed by laminating and combining a plurality of substrates composed of conductive layers and insulating layers, in which is formed a The connection hole for the power supply terminal of the electronic component installed on the surface of the multilayer circuit board so as to be connected with the first conductive layer includes the steps of: A detection portion having a detection hole is formed on a second conductive layer, the second conductive layer is on the back side relative to the first conductive layer; forming a through hole penetrating from the surface to the back surface of the multilayer circuit board while being in contact with the surface conductive layer, and in contact with the first conductive layer located inside, and by having a diameter smaller than that of the detection hole, wherein the surface conductive layer is provided on the surface of the substrate located on the surface; plating the inner surface of the through hole; and Along the through hole from the back side of the multilayer circuit board, by means of a tool having a diameter larger than that of the detection hole, while providing the tool and the detection portion thereon. Applying a predetermined voltage between the second conductive layers, additionally drilling a hole with a large diameter and a predetermined depth based on the detection of the detection hole; wherein said connection hole is formed through said via hole between said surface conductive layer and said first conductive layer, wherein plating is left on said inner surface thereof; wherein said first conductive layer is a conductive layer on a surface side of a second substrate adjacent to a surface substrate having said surface conductive layer; and The second conductive layer is a conductive layer on the surface side of the third substrate adjacent to the backside of the second substrate. 2. The method of manufacturing a multilayer circuit board according to claim 1, wherein the predetermined depth is a depth determined based on a position of the tool when the voltage becomes a preset value or less. 3. The manufacture method of multilayer circuit board as claimed in claim 1, also comprises the step: Next to the through hole, drilling a detection through hole at a position connected to the second conductive layer having the detection part; and Plating the inner surface of the detection through hole; wherein The predetermined voltage is applied between the second conductive layer having the detection portion and the tool by means of the plating of the detection through hole.

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